Figure 2. Verification of InsP₃R-1 dependent channel activity.

A–F, single sweeps from multiple cells following a pulse to −50 mV. A, recording from WT InsP₃R-1 in the absence of ADO. B, presence of ADO. C, DT40-3KO cells (InsP₃R null cells). D, ADO in the presence of the InsP₃R antagonist heparin. E, from a stable DT40-3KO cell line expressing S2+ splice variant D2550A InsP₃R-1, a ‘pore-dead’ mutant InsP₃R-1. F, from a stable DT40-3KO cell-line expressing S2+ splice variant V2548I InsP₃R-1, a mutation in a residue in the putative pore of InsP₃R-1 which corresponds to the residue present in ryanodine receptors. G, all-points amplitude histogram; red and blue traces are Gaussian fits of the data. H, I–V relationship for the WT and V2548I InsP₃R-1.